True - paper money is potentially garbage (in SHTF nightmares, for example), but for now, you can use it to pay almost any bill or buy about anything. You don’t need gold or silver (et al), to make normal transactions within the USA. Cash will do fine (for now). And, how much to have? Simple - figure out what your monthly expenses are, add a fudge factor (say, 25% or so), and oila! - you have your cash needs (which can be stored in your checking account, your wallet or purse, and wherever else is safe(ish).

This, as several have pointed out depends on the length and how widespread the SHTF situation is.
Cash right this moment has no actual intrinsic value but we still use it.
In a limited SHTF situation(Hurricane or earthquake) cash may be useless short term but in time or geographically further from the area it will be fine.
In and extended event (widespread grid down) it could take years to recoup. Paper money virtually useless.
So things with intrinsic value (gold /silver) and supply items (guns / ammo etc.) are what’s needed.

Obviously, when a disaster occurs, paper money does not become instantaneously worthless in the minds of 99% of people. Even in the immediate aftermath of a national/global catastrophe, there are those who will still believe cash has value, however stupid you think that to be.

Silver and/or gold may or may not be useful, as most folks have NO idea of its value now, let alone after a catastrophe. Again, much depends upon the situation and the people involved. No absolutes here.

I personally think it a mistake to pay for something with ammunition. I, myself, am not going to give anyone the means to shoot me. Period. I also will not accept ammunition as a form of payment. I have PLENTY already. Indeed, if someone offers me ammunition, my first thought is to “remove” them as a threat. I’d rather deal with them now than when they decide to fire it at me.

Still, I recommend keeping several thousand dollars in cash spread out in numerous secure locations. Price gouging, weeks of chaos, and bribes could go through cash very quickly. And, that’s not counting prostitutes. (Did I mention storing lube and condoms?)

25% each and add 25% SKILLS to survive and a skill that you can barter! Can you tan hides? Have equipment to harvest grain after an emp? Grind flour/bake bread in a wood fired oven? Brew beer to trade(I am going to be popular!) etc etc etc…

It will take a GROUP to survive unless you live 400 miles in the boonies with no neighbors for 50 miles any direction. I live in a small farming community of less than 300 in SW MN. We have varied skills in town but enough to keep us ALL alive!